So far I'm going with "strict story structure exercises are helpful".
I was once in a multi-week writing workshop thingie with a guy who told us a useful mantra he learned from his improv group. It took all the fear out of performance, he said. It was this:
I suck and I love to fail!
I repeat this to myself whenever I'm working on a first draft. I suck and I love to fail! Because that's what the first draft is gonna do, and it's okay.
Somebody say something rah-rah-ish. Or entertaining. Or distracting. Or perhaps make a startling post to your own LJ. I have to write a semi-comic scene next, with Giles and Willow oblivious to a quietly-freaking Tara, but first I need to procrastinate. It's vitally important that I procrastinate.